Republican Rep. Michele Bachmann’s presidential campaign is under investigation by the Office of Congressional Ethics, The Daily Beast reports.

Federal investigators are interviewing former Bachmann campaign staff members about “alleged intentional campaign-finance violations,’’ the online magazine said Monday.

“The investigators are working on behalf of the Office of Congressional Ethics, which probes reported improprieties by House members and their staffs and then can refer cases to the House Ethics Committee,’’ the magazine said.

According to the Beast report, Peter Waldron — a former Bachmann staffer who had a falling out with his ex-boss involving allegations he made of improper payments by the campaign — has been quizzed in the probe.

William McGinley, a lawyer for Bachmann, confirmed to the Beast that the Office of Congressional Ethics was eyeing her presidential campaign last year.

But he added, “There are no allegations that the congresswoman engaged in any wrongdoing.’’

“We are constructively engaged with the OCE and are confident that at the end of their review the OCE Board will conclude that Congresswoman Bachmann did not do anything inappropriate,’’ McGinley told the Beast.

According to the magazine, ex-staffers have been grilled about “allegations of improper transfer of funds and under-the-table payments actions by Bachmann’s presidential campaign, specifically in relation to the campaign’s national political director, Guy Short, and Bachmann’s one-time Iowa campaign chairman, state Sen. Kent Sorenson.’’

Sorenson and Short did not return separate calls for comment, the Beast noted.